Investigation of optical and structural properties of metal phthalocyanine doped TiO2 films prepared by sol-gel method

Today, Titanium dioxide (TiO2) is a material that is widely used and researched due to its superior properties such as brightness, non-toxicity, pure whiteness, physical and chemical stability. It is also used in various areas due to its low cost. Another material that is widely researched today is phthalocyanines, which are macromolecules. Since several different molecules can be attached to the main structure of phthalocyanines at the same time, it enables them to be used in various reactions and is an important factor that increases the application areas of phthalocyanine compounds. Thanks to their high physical and chemical stability, they are the center of attention in advanced research topics such as sensors and solar cells. In this thesis, undoped and different concentrations of various metal phthalocyanine doped TiO2 thin films were coated on glass substrates using the sol-gel spin coating method. The solution prepared for the coating process contains titanium (IV) n-butoxide, acetic acid and ethanol. Phthalocyanines used in the coating were used after being dissolved in N, N Dimethylformamide (DMF). Pure TiO2 films containing different concentrations of metal phthalocyanine were coated on glass substrate in 5 layers. The surface and optical properties of the coated films were examined using scanning electron microscopy (SEM), UV-Vis spectrophotometry, respectively. The film was annealed at 550° C for 90 minutes before the XRD analysis to form a crystalline structure. When the optical properties of the prepared films were examined, it was observed that the forbidden energy gap of pure TiO2 films was 4.04 eV, high transmittance and low absorption. On the other hand, it was determined that the optical properties of the phthalocyanine-added films vary according to the concentration ratio, the phthalocyanine substituent group used and the type of metal in the center. The annealed pure TiO2 films were found to contain anatase (101) -brookite (121) mixed phase. In all MPc-doped films, it was determined that brookite structure disappeared with the first doping (TiO2/Pc(I-V) and the crystal structure formed was anatase. It was determined that parameters such as crystal size, stress, dilocation density and the angle at which the peak was formed vary according to the concentration ratio of phthalocyanines forming the doped films, the phthalocyanine substituent group used and the type of metal in the center. Therefore, it is thought that the films prepared in this thesis can be used in applications involving organic-inorganic semiconductors such as optical filters, electrochromic devices, LEDs and solar cells.